Totally enclosed nonventilated motor



Jan. 4, 1949. R- LUDWIG 2,453,010

TOTALLY ENCLOSED NONVENTILATED MOTOR Filed March 20, 1947 WITNESSES:INVENTOR F Leon 1?. Ludwz' BY y 7160.4. w m MAW ATTORNEY Patented Jan.4, 1949 TOTALLY ENCLOSED NONVENTEATED MOTOR Leon R, Ludwig, Buflalo, N.Y., assiznor to Westinghouse Electric Corporation,

East Pittsburgh,

a corporation of Pennsylvania :Applic'ation March 20, 1947, Serial No.735,838

11 Claims. 1

My invention relates to totally enclosed dynamo-electric machines ofthe'type known as nonventilated, that is, a type having no external fansor blowers. the type to which my invention relates, the air which iscontained within the machine is totally enclosed, by means ofimperforate end-brackets which enclose the entire ends of the machine.While my invention is not altogether limited to one particular type ofmachine, it is primarily adapted for, and will be described inconnection with, a totally enclosed non-ventilated inductionmotor havinga cast squirrel-cage winding.

Totally enclosed motors are used in places where the external air isladen with either sizable chips, filings or other solid particles, oreven soft fiuffy particles like lint. The total enclosure is for thepurpose of keeping these airborne particles from clogging up the air-gapof the machine, or adhering to other air-passages or to the surface ofthe winding-insulation, thus interfering with heat-transfer. Theairgaips of commercial squirrel-cage motors, in the range between 5horsepower and 75 horsepower, more or less, are vulnerable to suchcontamination, because it is necessary to make these airgaps as small asis mechanically possible, in conformity with a reasonable cost ofmanufacturing and maintenance, in order to secure theperformancecharacteristics which are required of these general-utilitycommercial motors.

When the external air is not too linty, fancooled totally enclosedmotors are usable, having an external fan for blowing the external airover the outside of the total enclosure, for cooling the same. However,when the external air is quite linty, even this external fan cannot beutilized, because the lint adheres to the fanblades and quicklyinterferes with their eifective functioning. It is for this type ofservice that my improved motor is primarily designed.

The primary object of my invention is to produce a totally enclosednon-ventilated motor which will be as small in size and as low in cost,as is possible, while still achieving the required commercialperformance-characteristics. One of the first items, in the cost ofmanufacturing an induction motor, is the cost of the primary copper. Theprimary copper consists of insulated copper conductors, which must bewound and processed, and must then be laboriously inserted into thestator-slots, at a considerable laborminum), is relatively inexpensive,because it is.

In totally-enclosed machines of resistance increases rapidly with itstemperature,

so that, if the primary copper is worked at a high temperature, moreprimary copper will be needed, thus increasing the cost of this most,

costly part of the motor.

However, all totally enclosed motors are characterized by much higheroperating-temperatures than open or protected motors. The highoperating-temperature does not particularly harm the rotor-member,because it consists of a bundle of iron laminations with an integrallycast a1u-' minum squirrel-cage winding. A high temperature increases theresistance of the aluminum squirrel-cage winding, but this can be offsetby using more aluminum, which, as has been pointed out, does not costmuch, because it is cast. The stator-iron, that is, the stator-core andthe frame, necessarily run hot. in an enclosed motor, because all of theheat of the stator, plus the heat of the rotor, must find its way outthrough the stator-frame. The high temperature does not materiallyaffect the magnetic properties of the iron.

It is an object of my invention, therefore, to provide an improvedmotor, of this type, in which the primary copper is kept relativelycool, cooler than the primary iron. To this end, I line the stator-slotswith exceptionally thick slot-liners of a material which is chosen forthe highest available heat-insulating properties. To this end,

also, I provide improved ventilating-means for the end-turnsof theprimary windings, so that the heat which is ventilated in the primarywindings is withdrawn from these end-turns.

More specifically, it is an object of my invention to provide animproved end-turn ventilatingmeans which is featured by specialend-brackets having both internal and external heat-transfer fins.

With the foregoing and other objects in view, my invention, consists inthe combinations, systems, assemblies, structures, parts and cooling andmanufacturing means and methods herein acsaoro after described andclaimed. and illustrated in the accompanying drawing, wherein Figure 1is a longitudinal sectional view of the top hall of a motor embodying myinvention.

Fig. 2 is an end view of the leit-hand hall? of the motor. and

Fig, 3 is an inside end-view of the right-hand half or the left-handend-bracket, removed.

In the illustrated form 01 embodiment of my motor, there is astator-member 4 and a laminated stator-core 5 with a cylindricalairgap-bore t therein. The stator-core ii is provided withwinding-receiving slots 1, which are lined with unusually thick, andhigh heat-insulating, slot liners I. The stator-slots 1 receive thestraight coil-sides ill of a primary winding I l, having enchturns l2projecting from each end of the stator" 002'0.

The machine also has a rotor-member it having a cylindrical laminatedrotor-core it which is carried by a shaft ii. The rotor-core is providedwith a die-cast aluminum squirrel-cage winding II, in a known manner.The rotor is also provided with two Ian-means il, one at each end or therotor-core. These fan-means may be either separate from thesquirrel-cage member IE, or they may be cast integrally therewith, in aknown manner. I have illustrated the Ian-means H as being castintegrally with the squirrel-cage winding Hi. It is desirable, inaccordance with my invention, that the two tan-means II shall not be invery close thermal or heat-conducting relation to the squirrel-cagewinding l8, because it it quite permissible tor the squirrel-cagewinding it to run hot, but it is very urgent that the primaryend-windings 12 shall run as cool as possible, and hence it is desirablethat the two fan-means I1, which are disposed under the end-turns [2, atthe two ends of the machine, shall run cool, so as not to unduly heatthe internal air which is utilized to cool the stator end-turns l2. Inorder to minimize the rate oi heat-transfer between the squirrelcagewinding i6 and the two sets of Ian-blades I1, I utilize reduced-areaneck-portions l8 for Joining the Ian-blades to the end-rings o! thesquirrel-cage winding It,

The motor also comprises two imperiorate, machine-enclosing,bearing-supporting bracketmeans 20, one at each' end of the machine. Inaccordance with a preferred form of embodiment of my invention, eachbracket-means is composed essentially of two parts, of dissimiliarmetals, comprising first a bracket-proper 2|, having a centrallylocated, shaft-supporting bearing 22, and a radially outwardly andaxially inwardly extending cup-shaped portion 23, having its rim 24substantially air-tightly secured to the stator-member I, at therear-portion or outer diameter of the core 5 or of a surroundingstatorframe 25, so that the stator end-turns l2 are enclosed, withaspace between said end-turns and the bracket at each end..oi' themachine. The brackets 2| are made from a metal which is chosen for arelatively high strength and a relatively high melting-point.

As it is desirable for the bracket 2! to run as cool as possible, inorder to provide the maximum cooling-effect for the stator-end turns I2,it is desirable to have the rims 24 of the cup-shaped bracket-portions23 in poor heat-exchange relation to the stator-member, which may beaccomplit lished by utilizing suitable heat-insulating gaskets 20. asshown.

The cup-shaped portion 23 of each bracket 2i.

is provided with perforations, preferably in the term of slots ill,which are closed, by means oi a cast lieat transfer metal-portion, orbracketcovering Ml, which is made of a metal havins relatively lowstrength, relatively light weight, and a relatively low melting-point.Each heattranoioi: bracket-covering 30 has an inner portion iii wlriiohcompletelyiincs the inside of its cupshapeol hracket nortion 23, and anouter portion completely lining the outside oi its cup-shapedbraoltotmortion 2-", with integral joining-portions 3t filling thebracket-perforations 2'! and joining the inner and outer lining-portionsSI and til at the heat-"transfer bracket-covering 2|). The outerlining-portion ill may be provided with external llfihll l'hfiliitlllgfins M, which may be advantageously shaped to that they fill or occupythe ordinarily unused curved spaces at the outsides oi the curvedcup-portions 23 of the endbracltets, so that the overall contour of themotor, including the external flns 34, shall be substantially acompletely filled cylinder, as indicated in Fig. l. lit is usuallydesirable also to provide internal heat-transfer ilns 35 on the innerlining 3i of the bracket-covering 30.

It is usually desirable to make the bracketproper 2! of steel, and o! asize and weight which is the smallest possible, in consideration of itsprimary function of supplying the necessary mechanical strength andrigidity. It is usually desirable to make the heat-transfer metalliningportion an of aluminum, or other light-weight, low-melting-pointmetal, having a sufficient heatconductivity. The aluminum covering 30 ispreferably cast integrally in place on its perforated steel bracket 2|,so that the whole bracket-assembly 20 is an imperiorate bracket,imperforate in the sense of having no ventilatingopenings, and having adirect metal heat-transfer path from the internal fins 35 to theexternal fins 34.

As previously intimated, the design of my machine is such that all partsof the machine run quite hot, except the primary winding I I, the twofan-means i1, and the end-brackets 20. In operation, each of theIan-means l1 sets up a lively circulation of the internal air which istrapped within the bracket 20 at that end of themachine. This air blowsradially outwardly over and around the primary end-turns i2, and henceaxially outwardly and radially inwardly over the inner lining 3 IV ofthe bracket, giving up its heat to the internal fins 35, and thencereturning. cooled, to the fan for recirculation. The bracket-lining orcovering 30 carries away the heat, by direct metallic conduction, fromthe internal fins 35 and the inner lining 3|, through the integraljoining-portions 32 which fill the bracket-slots 21, to the integralouter lining 32 and the integral external fins 24, from which the heatis directly radiated to the external atmosphere which surrounds themotor. The slot-lining coil-sides ill of the primary winding ii arecooled by metallic heat-conduction through the copper of the primarywinding, from the end-turns I2 at the two ends or the machine. Theextra-heavy, extra-insulating slot-liners B serve to prevent the heatingor the coil-sides Ill from the relatively hot stator-core 5. The heat ofthe rotor-member l3, as well as the heat-losses in the stator-iron 5,eventually find their way out through the stator-core 5 and thestator-frame 25, from which the heat is radiated to the externalatmosphere.

An important incidental advantage of my invention is that the brackets2! run cool, and hence broadest construction consistent with their Ilanguage.

I claim as my invention:

1. A totally enclosed non-ventilated dynamoelectric machine comprising astator-member having a stator-core with an airgap-bore therein, and astator-winding having end-turns projecting from each end or thestator-core, a rotormember having a rotor-core rotating within thestator-bore, said rotor-member also including a shaft and two fan-means,one under each 0! the lying coil-sides, the primary core having slotsfor said coil-sides, and slot-liners of good heat-insulating qualities,the two fan-means being in poor heat-exchang relation to thesquirrel-cage winding. the stator and rotor cores having substantiallyno axially extending ventilating-openings therethrough so that theventilation established by each Ian-means is confined to.the aforesaidventilating space at its own end or the machine. the heat-dissipatingconditions and the electrical design being such that the rotor-memberand the stator-core both operate at a higher temperature than theprimary windings and the two Ianmeans, the primary windings and thebearings stator end-windings at the two ends of the machine, twoperforated machine-enclosing, bearingsupporting brackets, one at eachend oi the machine, each bracket having a centrally locatedshaft-supporting bearing and a radially outwardly and axially inwardlyextending cup-shaped portion having its rim substantially air-tightlysecured to the stator-member, so that the stator end-turns are enclosed,with a ventilating space between said end-turns and the bracket at thatend of the machine, each bracket having a plurality of perforations inits cup-shaped portion, each bracket being made of a metal havingrelatively high strength and a relatively high melting-point, and a castheat-transfer metal-portion, of relatively low strength, relativelylight weight and a relatively low melting-point, associated with eachcupshaped bracket-portion, each heat-transfer metal-portion having aninner portion completely lining the inside o! its cupshapedbracket-portion, an outer portion completely lining the outside of itscup-shaped bracket-portion, integral joining-portions filling thebracket-perforations and Joining the inner and outer portions, andheat-radiating fins on the outer portion.

2. The invention as defined in claim 1, characterized by eachheat-transfer metal-portion also having heat-radiating fins on its innerportion. I

3. The invention as defined in claim 1, characterized by said machinebeing a squirrel-cage induction-motor having a cast squirrel-cagewinding on the rotor-core, the stator-winding being the primary windingand having straight slotlying coil-sides, the primary core having slotsfor said coil-sides a-nd slot-liners of good heat-insulating qualities,the stator and rotor cores having substantially no axially extendingventilatingopenings therethrough so that the ventilation established byeach tan-means is confined to the aforesaid ventilating-space at its ownend or the machine, the heat-dissipating conditions and the electricaldesign being such that the rotor-member and the stator-core both operateat a higher temperature than the primary winding, the primary windingsand the bearing being cooled by the heat-transfer metal-portions.

4. The invention as defined in claim 1, characterized by said machinebeing a squirrel-cage induction-motor having a cast squirrel-cagewinding on the rotor-core, the stator-winding being the primary windingand having straight slotbeing cooled by the heat-transfermetal-portlons.

5. The invention as defined in claim 1, characterized by said machinebeing a squirrehcage induction-motor having a cast squirrel-cage windingon the rotor-core, the stator-winding being the primary winding andhaving straight slotlying coil-sides, the primary core having slots forsaid coil-sides and slot-liners of good heat-insulating qualities, therims 01 the cup-shaped portions of the two bracket-s being in poorheat-exchange relation to the stator-member, the stator and rotor coreshaving substantially no axially extending ventilating-openingstherethrough so that the ventilation established by each fanmeans isconfined to the aforesaid ventilatingspace at its own end of themachine, the heatdissipating conditions and the electrical design beingsuch that the rotor-member and the statorcore both operate at a highertemperature than the primary windings, the primary windings and thebearings being cooled by the heat-transfer metal-portions.

6. A totally enclosed non-ventilated squirrelcage induction-motorcomprising a stator-member having a stator-core with an airgap-boretherein, and a stator-winding having end-turns projecting, from each endof the stator-core, the stator-winding being the primary winding andhaving straight slot-lying coil-sides, the primary core having slots forsaid coil-sides and slot-liners of good heat-insulating qualities, arotor-member having a rotor-core rotating within the' stator-bore, acast squirrel-cage winding on the rotor-core, said rotor-member alsoincluding a shaft and two tan-means, one under each of the statorend-windings at the two ends of the machine, two imperiorate,machine-enclosing, bearing-supporting bracket-means, one at each end ofthe machine,- each bracket-means having a centrally locatedshaft-supporting bearing and a radially outwardly and axially inwardlyextending cup-shaped portion having its rim substantially air-tightlysecured to the stator-member, so that the stator end-turns are enclosed,with a ventilating space between said end-turns and the bracket-means atthat, end of the machine, and external heat-radiating fins on eachcup-shaped bracket-portion. the stator and rotor cores havingsubstantially no axially extending ventilating-openings therethrough sothat the ventilation established by each tan-means is confined to theaforesaid ventilating-space at its own end of the machine, theheat-dissipating conditions and the electrical design being such thatthe rotor-member and the stator-core both operate at a highertemperature than the primary'windings, the primary windings and thebearings being cooled by the external heat-radiating fins or thecup-shapedbracket-portions. I

7. A totally enclosed non-ventilated squirrelcage induction-motorcomprising a stator-memstator-bore, a cast squirrel-cage winding on therotor-core, said rotor-member also including a shaft and two Ian-means,one under each or the stator end-windings at the two ends 01' themachine, the two tan-means being in poor heat-exchange relation to thesquirrel-cage winding, two imperforate, machine-enclosing, portingbracket-means, one at each end or the machine, each bracket-means havinga centrally located shaft-supporting bearing and a. radially outwardlyand axially inwardly extending cupshaped portion having its rimsubstantially airbearing-supcore, said rotor-member also including ashaft and two tan-means, one under each of the stator end-windings atthe two ends 01 the machine, two impertorate, machine-enclosing,bearing-supporting bracket-means, one at each end or the machine, eachbracket-means having a centrally located shaft-supporting bearing and aradially outwardly and axially inwardly extending cupshaped portionhaving its rim substantially airtightly secured to the stator-member, sothat the stator end-turns are enclosed, with 'a ventilating spacebetween said end-turns and the bracketmeans at that end of the machine,and external heat-radiating fins on each cup-shaped bracketportlon, thestator and rotor cores having substantially no axially extendingventilating-openings therethrough so that the ventilation established byeach fan-means is confined to the aforesaid ventilating-space at its ownend of the machine, the heat-dissipating conditions and the electricaldesign being such that the rotor-member and the stator-core both operateat a higher temperature than the primary windings and the two fan-means,the primary windings and the bearings being cooled by the heat-transfermetalportions.

8. A totally enclosed non-ventilated squirrelcage induction-motorcomprising a stator-member having a stator-core with an airgap-boretherein, and a stator-winding having end-turns projecting from each endof the stator-core, the stator-winding being the primary winding andhaving straight slot-lying coi1-sides, the primary core having slots forsaid coil-sides and slot-liners of good heat-insulating qualities, arotor-member having a rotor-core rotating within the statorbore, a castsquirrel-cage winding on the rotortightly secured to the stator-member,so that the stator end-turns are enclosed, with a ventilating spacebetween said end-turns and the bracketmeans at that end of the machine,and external heat-radiating fins on each cup-shaped bracketportion, therims 01 the cup-shaped portions of the two brackets being in poorheat-exchange relation to the stator-member, the stator and rotor coreshaving substantially no axially extending ventilating-openingstherethrough so that the ventilation established by each fan-means isconfined to the aforesaid ventilating-space at its own end of themachine, the heat-dissipating conditions and the electrical design beingsuch that the rotor-member and the stator-core both operate at a highertemperature than the primary windings, the primary windings and thebearings being cooled by the external heat-radiating fins of thecup-shaped bracket-portions.

9. The invention as defined in claim 6, characterized by each cup-shapedbracketportion also having internal heat-transfer fins.

10. The invention as defined in claim 7, char acterized by eachcup-shaped bracket-portion also having internal heat'transfer fins.

11-. The invention as defined in claim 8, characterized by eachcup-shaped bracket-portion also having internal heat-transfer fins.

LEON R. LUDWIG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,087,166 Gray Feb. 1'7, 19142,185,740 Smith Jan, 2, 1940 2,321,126 Breuer June 8, 1943

